How can I tell the difference between if i gained fat or gained muscle? 2 weeks ago i joined a gym, and have been there every day since then except last saturday. Yet i gained weight. But before i joined the gym, i lost 13 lbs. When i joined, i began to gain. My maximum weight lifting amount has increased though. I also feel skinnier. But i really dont understand.

Im a tad confused, but to give my best possible insight i would recommend perhaps properly calculating youre body fat % and see if it has either increased or decreased and then you can come up with some possible conclusions. You can do this using a fat caliper device, or also at home doing some complex measurements and then caluculating them accordingly based on a body fat calculator available online on certain websites. Hope this helps